High precision syringe



Jan. 30, 1968 G. A. KLOEHN HIGH PRECISION SYRINGE Filed Oct. 23, 1965 v INVENTOR. I GARTH A. KLQEHN p vx 1 w a hm N AZ u A; @m mm United States Patent 3,366,286 HIGH PRECISION SYRINGE Garth A. Kloehn, 2330 El Rancho Drive, Whittier, Calif. 90606 Filed Oct. 23, 1965, Ser. No. 503,672 12 Claims. (Cl. 222-386) This invention relates to syringes and more particularly to a high-precision high-pressure syringe having an improved inexpensive barrel equipped with simple, adjustable, highly reliable and eificient means for detachably securing both the plunger and the needle to the respective ends of the barrel in a fluid-tight manner. The barrel bore is of uniform diameter between its opposite ends but need not have a sealing fit with the plunger owing to the provision of fluid-tight seals between the rims of the bore ends and the supporting means for the plunger and dispensing facilities respectively. Each of these facilities comprise cup-shaped members secured to the opposite ends of the barrel and resilient tubular means carried thereby and designed to have their inner ends resiliently compressed into sealing engagement with the adjacent rim edges of the bore ends. This compressive force is preferably adjustable as necessary to assure a seal and additionally to vary the pressure and frictional engagement between the plunger and the tubular sealing member. The dispensing tube may be similarly held sealed to the other end of the bore or detachably coupled to the tapered outer end of the resilient tubular member.

The present invention represents certain improvements in the syringe of the type disclosed in my copending application for United States Letters Patent Ser. No. 350,165, filed Mar. 9, 1964, now Patent No. 3,223,282, entitled, Precision Measuring Syringe. The construction of the present invention is simpler, utilizes fewer parts, is more economical to manufacture and maintain, and exhibits certain advantages over my prior design. Additionally,

it utilizes a fewer number of dimensions required to be held to close manufacturing tolerances without sacrificing efficiency or the accuracy of the results obtainable therewith.

The present construction features a one-piece barrel having a central bore. Generally, similar end fittings at the opposite ends of the barrel each include a pair of nonmetallic components including an end cap having a forced, highstrength fluid-tight friction fit with a respective end of the barrel. According to one preferred embodiment of the invention, each of these end caps has a bore through its bottom threaded to mate with the threaded shank of a nonmetallic packing gland or bushing. One of these bushings supports and provides a fluid-tight running seal with the plunger, whereas the other forms a fluid-tight support and seal for a hollow needle as well as means for holding the needle forcibly seated against the discharge end of the barrel bore. Preferably, the plunger has a free sliding fiit within the barrel bore and depends on light pressure contact with the supporting bushing to provide a fluid seal. Accordingly, a precision fit and fluid seal with the barrel bore is unnecessary, thereby avoiding the need for mutually-cooperating high manufacturing tolerances between the plunger and bore wall heretofore considered essential in syringes of this type. A scale, preferably coextensive in length with that of the barrel bore, is calibrated to represent the volumetric displacement of the plunger rather than the volumetric capacity of the bore.

Owing to the design and materials from which the plunger supporting bushing is formed, precise manufacturing tolerances at the plunger end of the barrel are dispensed with and it is a simple matter to align the end of the bushing with the end of the bore. Because of this feature hang-up of the plunger end with the bore end owing to slight manufacturing discrepancies between the bore and the sealing assembly supporting the plunger and customarily experienced in syringes of prior design, is entirely avoided. The same remarks apply equally to the needlesupporting end of the syringe for reasons which will become apparent from following portions of this disclosure. Various other features and advantages of the present construction will appear from the detailed description and the annexed drawing.

Accordingly, it is a primary object of the present invention to provide a new and improved high-precision syringe characterized by its simplicity, ruggedness, accuracy, and its ease of manufacture and servicing.

Another object of the invention is the provision of a l b-precision syringe featuring a minimum number of components and the simplicity of the means utilized to hold the parts assembled.

Another object of the invention is the provision of a syringe having an improved and simplified adjustable assembly for holding the plunger assembled to one end of a transparent barrel.

Another object of the invention is the provision of a syringe having a simple, rugged and improved assembly for holding a hollow needle detachably coupled to the discharge end of the barrel.

Another object of the invention is the provision of a syringe having wells and cooperating coupling assemblies mounted coaxially of its ends and of a through bore and featuring cooperating resilient bushing members one of which is utilized to hold a plunger sealingly aligned with one end of the bore and the other of which is used to hold a hollow needle sealingly assembled to the other end of the bore.

Another object of the invention is the provision of a high-pres-sure, high-precision syringe having end assemblies held securely assembled in fluid-tight manner by a forced telescopic fit with the barrel end.

Another object of the invention is the provision of a syringe having a high accuracy plunger held sealed to and aligned with one end of a barrel bore by a one-piece adjustable bushing effective to provide a seal with the barrel bore as well as with the side walls of the plunger.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawings to which they relate.

Referring now to the drawings in which preferred embodiments of the invention are illustrated.

FIGURE 1 is a side view of one preferred embodiment of the invention syringe ready for use;

FIGURE 2 is a fragmentary sectional view on an enlarged scale of FIGURE 1 and showing parts broken away to illustrate constructional details;

FIGURE 3 is a cross-sectional view taken along line 3-3 on FIGURE 2;

FIGURE 4 is an enlarged fragmentary View of the needle end of a second preferred embodiment.

Referring first more particularly to FIGURES 1, 2 and 3, there is shown one preferred embodiment of a highpressure, high-precision syringe designated generally 10. This syringe includes a thick-walled barrel 11 formed of any suitable transparent material, as glass or plastic. This barrel is provided with an accurate central bore 12 opening at its opposite ends into counterbores or wells 13, 14. As here shown, the bottoms of both wells are flat but it will be understood that, if desired, each may be provided with a conical counterbore merging with the adjacent end of bore 12.

The left-hand end of the barrel, as shown in FIGURE 2, is provided with a plungersupporting assembly designated generally 16 and including a cup-shaped member 17 formed of a suitable nonmetallic elastomeric. Kel-F,

a polymer of trifluorochloroethylene is a particularly suitable material because of its many favorable properties for this application. Member 17 includes generally cylindrical side walls sized to have a forced friction fit with the exterior surface of barrel 11. It is found that this material is easily assembled over the transparent barrel and forms a permanent high strength fit and a fluid-tight junction which substantially defies efforts to separate the parts. The skirt of member 17 is preferably shorter than the length of Well 13 with the result that the inner end of the well and its junction with bore 12 are fully visible from the exterior of the syringe.

The second and remaining component of the plunger assembly includes a bushing 19 having a long, generally cylindrical shank 20 having threads 21 mating with complemental threads in the bottom of cup member 17. The inner end of shank 20 is beveled, as shown at 22, and terminates in a very narrow radius end adapted to form a high pressure seal against the rim edge of bore 12. Bushing 19 is formed with a shouldered central bore 24 the inner end of which has a close sliding fit with the precision surface of plunger 25. The latter is preferably formed of stainless steel or the like and its outer end is provided with a thumbpiece 26.

The multiple-function, highly important bushing 19 is preferably formed of resilient elastomeric material, Teflon being particularly satisfactory and suitable. Plunger 25 is free of contact with the bore through this bushing except for the inner one-third of its length where it has a close running fit with the plunger. However, upon tightening of bushing 19 to press its inner conical end against the bottom of Well 13, it is found that the compression of the free and unsupported length of the bushing enclosed by well 13 not only forms a high pressure fluid seal with the rim edge of the bore but also provides a readily adjusted fluid-tight seal with the plunger itself. The combined bushing and packing gland 19 is usually adjusted while the inner end of the plunger is held substantially flush with or slightly within the adjacent end of bore 12. As the user starts to tighten bushing 19, the other hand may be employed to move the plunger back and forth a slight amount to make certain that the plunger is accurately aligned with bore 12. Owing to the nature of the bushing material, it is easily possible to fiex the inner end of the bushing by any slight amount required to provide accurate alignment of the plunger with the bore in a smooth operating relationship. Thereafter, the bushing is tightened further if necessary to provide the requisite seal and resistance to movement of the plunger lengthwise of the supporting assembly 16.

The needle supporting assembly designated generally provided at the other end of the barrel includes a cupshaped member 31 of the same general construction and of the same material as member 17 for the plunger assembly. The needle supporting and adjusting bushing 32 will be understood as having the same general construction as bushing 19 and includes a long, unthreaded shank 33 provided with threads 34 at its outer ends mating with threads in the bottom of member 31. The inner conical end 35 seats against the rim edge of bore 12 in the bottom of well 14. The inner smaller diameter end of bore 36 through the bushing has a press fit with the exterior of hollow needle 37. This needle is inserted to lie flush with the smaller end of bushing 32. Thereafter, the bushing is rotated to tighten it against the rim edge of the bore placing the shank of the bushing under axial compression and forming a high pressure fluid seal with both the end of the bore and with the exterior surface of needle 37. Desirably, the diameter of the inner end of the bushing is greater than bore 12 to assure to positive seal with the adjacent end of the bore during the assembly operation.

Extending along one side of barrel 11 is a suitable scale 40 having its zero graduation mark 41 located radially opposite both the bottom of well 14 and the inner end of needle 37. Similarly, the highest scale graduation 42 is located at the opposite end of bore 12 radially opposite the bottom of well 13. As will be apparent from FIGURE 1, the opposite ends of scale 4-0 are spaced inwardly from the adjacent ends of mounting assemblies 16 and 39, respectively, thereby enabling the user to View the opposite ends of the bore at all times and to ascertain that the inner end of the needle is flush with the zero graduation mark and that the opposite end of bore 12 is directly opposite scale graduation 42. This arrangement also facilitates checking the position of the plunger end at all times and particularly as to when it is precisely opposite the ends of bore 12.

Referring now to FIGURE 3, attention is invited to another feature of the invention exemplified by a narrow thin strip 44 extending the full length of scale 12 and disposed along the barrel diametrically opposite scale 12. Strip 44 is formed of any suitable opaque material, as for example, a ceramic decal, its purpose being to provide a contrasting background for the scale graduations and rendering the latter more readily readable under widely varying lighting conditions. It will be understood that various materials other than a ceramic decal can be utilized for this background so long as the material resists abrasion, attack by acids, peeling, change of color, and is resistant to the high temperatures normally employed to sterilize syringes.

Referring now to FIGURE 4, showing an alternate mounting assembly for the needle, it will be understood that the same reference characters distinguished by a prime are used to describe the same or similar parts in the two embodiments. One of the major differences between the two embodiments resides in the fact that mounting assembly 30 is made entirely in one piece from elastomeric material such as Kel-F whereas the corresponding assembly in FIGURES l to 3 is formed in two parts of like materials. Projecting axially of the cup-shaped member 31 is a cylindrical member 45 of smaller diameter than the side wall of well 14 and having a conical inner end 35 seating against the rim edge of bore 12'. Member 45 is slightly longer than the depth of well 14 with the result that cup-shaped member 31' can be telescoped forcibly over the end of barrel 11' until the inner conical end 34' is firmly and forcibly seated against the rim edge of bore 12'. The parts are then held immovably assembled but should the syringe exhibit any tendency to leak across the end of the conical surface 35 it is merely necessary to apply pressure to the outer end of member 31' and force it into more complete assembly with the barrel thereby restoring the effectiveness of seal 35 even against very substantial syringe operating pressures, as, for example, pressures of 100, 200 psi. and higher.

Projecting axially outwardly from the exterior of member 31' is a frusto-conical mounting shank 49 for the complementally shaped luer 46 staked to the inner end of a hollow needle 37'. Needles having luers of this type are well known to workers in this field and have an inner seating surface 48 adapted to form a high strength friction fit with the tapered surface of shank 49. It is a simple matter to replace needles equipped with such conical luers.

In closing, it is pointed out that the radial flange provided at the outer end of cup-shaped member 17 for the plunger is preferably provided with a flat surface 49 on one side (FIGURE 3) serving to prevent the syringe from rolling about the laboratory counter. A further feature not pointed out before is the fact that the inner end portion of both the plunger bushing 19 and the needle mounting bushing 32 may be formed separately from the bushing itself if desired and has short generally cylindrical sleeves. In this case, the separate sleeve-like components are pressed against the respective bore ends by tightening bushings 19, 32 thereby placing the short sleeves in axial compresion.

While the particular high precision syringe herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. A high precision syringe having an elongated barrel formed with a single charge-receiving bore of uniform diameter extending lengthwise through said barrel, means for securing hollow dispensing means in fluid-tight relatron to one end of said bore, plunger means reciprocable lengthwise of said bore and having an operating end proecting beyond the other end of said bore, a supporting assembly for said plunger means including stationary means carried by the adjacent end of said barrel and having an axial threaded bore therethrough, and tubular means threadedly mounted in said threaded bore and having an inner resilient end closely embracing said plunger means, said tubular means being rotatable against the adjacent rim edge of said bore thereby placing said resilient end in axial compression to form and maintain a fluid-tight seal with said plunger means and with the adjacent rim edge of said bore.

2. A syringe as defined in claim 1 characterized in that sa1d means for securing said dispensing means to one end of said bore comprises a cup-shaped member of resilient material telescoped over one end of said barrel and including a resilient tubular member projecting axially from the opposite sides of the bottom of said cupshaped member, the inner end of the inwardly projecting portion of said tubular member being compressed against the rim edge of said one end of said bore to form a fluidtight seal therewith and the periphery of the portion of said tubular member on the outer side of said cup-shaped member being tapered and adapted to be detachably coupled to complementally tapered luer means of a hollow needle.

3. A syringe as defined in claim 2 characterized in that said means for securing said dispensing means to one end of said bore is formed as one unitary member of resilient elastomeric material.

4. A syringe as defined in claim 1 characterized in that said tubular means is effective when rotated to vary the frictional pressure between its inner surface and the juxtaposed surface of said plunger means in contact therewith.

5. A syringe as defined in claim 1 characterized in that said stationary means includes a non-metallic cupshaped member of non-metallic material the interior side wall surfaces of which have a slightly smaller internal diameter than said barrel and having a high strength frictional fit with said barrel end when forcibly telescoped thereover.

6. A syringe as defined in claim 1 characterized in that said means for securing said hollow dispensing means to one end of said bore includes end cap means secured to the adjacent end of said barrel and having a tubular member of resilient material mounted axially thereof with its inner end compressed in sealing engagement with the rim of said bore, and the outer end of said tubular memher having a tapering resilient surface for holding the luer of a hollow needle detachably coupled thereto.

7. A syringe as defined in claim 1 characterized in that said means for securing said hollow dispensing means to one end of said bore includes end cap means secured to the adjacent end of said barrel, elongated resilient bushing means threadedly supported axially of said end cap means and effective upon rotation to form a fluidtight seal with the inner end portion of said dispensing means and with the end surface of said barrel immediately surrounding the adjacent end of said bore.

8. A syringe as defined in claim 1 characterized in that said hollow dispensing means includes a non-metallic member telescoped over and secured to one end of said barrel, and a tubular extension of resilient material coaxially of the associated end of said bore and threadedly mounted in said non-metallic member, said tubular extension being manually rotatable to compress the inner end thereof in pressurized seating contact with the adjacent rim edge of said barrel bore and into pressurized sealing contact with the side wall of said hollow dispensing means immediately adjacent the rim edge of said barrel bore.

9. A syringe as defined in claim 1 characterized in that said plunger means has a diameter less than the diameter of said barrel bore and being freely reciprocable therealong without forming a fluid seal with said bore.

10. A plunger mounting assembly for a syringe, said assembly comprising a cup-shaped member the side wall of which is adapted to be telescoped over and secured to one end of a transparent tubular syringe barrel, a hollow bushing of resilient elastorneric material having a threaded shank mating with a threaded opening axially through the bottom of said cup-shaped member, said bushing having a conical end at one end and an enlarged outer end adapted to be gripped by the fingers to rotate the same relative to said cup-shaped member, and the bore through said bushing adjacent said conical end being sized to embrace closely and seal against the stem of a syringe plunger.

11. A plunger mounting assembly as defined in claim 10 characterized in that said bushing is formed of plastic composition.

12. A syringe needle mounting assembly for use in holding a hollow needle sealed against the outlet end of the bore in a syringe barrel, said assembly comprising a resilient non-metallic cup-shaped member adapted to be telescoped over and secured to one end of a syringe barrel, a hollow bushing of resilient elastomeric material having a threaded shank mating with a threaded opening axially through the bottom of said cup-shaped member, said bushing having an inner end adapted to be compressed in sealing engagement with the rim edge of a bore in a syringe bore and an outer end adapted to be gripped by the fingers to rotate the same relative to said cup-shaped member and the bore through said bushing being sized to embrace and seal against the shank of a hollow needle as the inner end of said bushing is axially compressed against the rim edge of a syringe barrel bore.

References Cited UNITED STATES PATENTS 793,099 6/1905 Sapp 128-218 880,433 2/1908 Wilson 128-218 1,117,701 11/1914 Platt et al. 128-218 1,240,033 9/1917 Dickinson 128-218 1,933,371 10/1933 Eastman 222-386 X 2,254,449 9/1941 Rassmussen 128-218 2,888,015 5/1959 Hunt 128-218 3,035,616 5/1962 Hamilton 128-218 3,101,711 8/1963 Reitknecht 128-218 3,108,592 10/1963 Hassing et al. 128-218 3,216,616 11/1965 Blankenship 222-386 FOREIGN PATENTS 1,076,743 4/ 1954 France.

WALTER SOBIN, Primary Examiner. 

1. A HIGH PRECISION SYRINGE HAVING A ENLONGATED BARREL FORMED WITH A SINGLE CHARGE-RECEIVING BORE OF UNIFORM DIAMETER EXTENDING LENGTHWISE THROUGH SAID BARREL, MEANS FOR SECURING HOLLOW DISPENSING MEANS IN FLUID-TIGHT RELATION TO ONE END OF SAID BORE, PLUNGER MEANS RECIPROCABLE LENGTHWISE OF SAID BORE AND HAVING AN OPERATING END PROJECTING BEYOND THE OTHER END OF SAID BORE, A SUPPORTING ASSEMBLY FOR SAID PLUNGER MEANS INCLUDING STATIONARY MEANS CARRIED BY THE ADJACENT END OF SAID BARREL AND HAVING AN AXIAL THREADED BORE THERETHROUGH, AND TUBULAR MEANS THREADEDLY MOUNTED IN SAID THREADED BORE AND HAVING AN INNER RESILIENT END CLOSELY EMBRACING SAID PLUNGER MEANS, SAID TUBULAR MEANS BEING ROTATABLE AGAINST THE ADJACENT RIM EDGE OF SAID BORE THEREBY PLACING SAID RESILIENT END IN AXIAL COMPRESSION TO FORM AND MAINTAIN A FLUID-TIGHT SEAL WITH SAID PLUNGER MEANS AND WITH THE ADJACENT RIM EDGE OF SAID BORE. 